1. Technical Field
The present invention relates to a developing cartridge capable of developing an electrostatic latent image on a latent image carrier by developer, a developing device, and an image forming apparatus.
2. Related Art
There is known an electrographic recording type image forming apparatus exposing and forming an electrostatic latent image on the surface of a latent image carrier on the basis of image data. This image forming apparatus forms an image by allowing a developing device to develop the electrostatic latent image using toner and transferring a toner image formed on the surface of the latent image carrier onto a record medium such as a record sheet. Recently, the electrographic recording type image forming apparatus has been generally designed so as to detachably mount a toner cartridge incorporated with or separated from a developing device and storing toner. In addition, when the stored toner is consumed by repeatedly developing the electrostatic latent image on the surface of the latent image carrier, the toner cartridge is exchanged to supplement toner for developing the electrostatic latent image on the surface of the latent image carrier.
In the developing device, since the toner in the developing chamber is agitated for a long time by an agitating member, a toner supply roller, and a regulation blade, a charging capability deteriorates. When the toner cartridge is exchanged and new toner and the deteriorated toner remaining in the developing chamber are agitated and mixed for use, the new toner with a high charging capability is selectively charged and the deteriorated toner is insufficiently charged. Therefore, since a total charge amount of the agitated and mixed toner becomes insufficient, control leakage or blushing to a non-image portion may occur. In order to prevent the control leakage or the blushing, for example, JP-A-2000-181216 discloses a technique for processing the deteriorated toner remaining in the developing chamber in such a manner that driving time of a developing device is counted to perform forcible writing in the non-image portion in accordance with the driving time and toner deteriorated in the charging capability in the developing chamber is consumed.
However, this known technique has a problem in that the toner different in a deterioration state (charging property) in the developing chamber coexist and the control leakage or the blushing may occur due to mixture of the toner different in the charge amount of toner.